February 20, 1824

Megalosaurus

William Buckland presents the first formal scientific description of Megalosaurus

Buckland opened by admitting that nothing close to an entire skeleton existed, and that almost none of the bones had been found touching one another.

20 February 1824, Geological Society of London

On 20 February 1824, William Buckland read "Notice on the Megalosaurus or great Fossil Lizard of Stonesfield" to the Geological Society of London. He was an Oxford geologist and the society's newly installed president.

The material was a set of isolated bones from Stonesfield, about 12 miles northwest of Oxford: a partial lower jaw with teeth, vertebrae, ribs, and pelvic and hind-limb elements. Apart from some connected vertebrae, none of it had been found in articulation.

Naming the great lizard

In concurrence with William Daniel Conybeare, Buckland applied the genus name Megalosaurus — "great lizard" — and argued from the teeth that the animal had been carnivorous. Mary Morland prepared the drawings used for the published plates.

From those scattered bones he estimated an animal about 40 feet long, comparing its bulk to that of a seven-foot-tall elephant. Georges Cuvier had examined the Oxford material and encouraged Buckland's reading of it as a giant extinct reptile.

A genus, not a species — and not yet a dinosaur

Buckland established only the genus. The valid species epithet, Megalosaurus bucklandii, came from Gideon Mantell in 1827, and the word "dinosaur" did not exist until Richard Owen coined Dinosauria in 1842.

The reading and the printing are separate events under zoological nomenclature: taxonomic availability came from the illustrated Transactions paper published later in 1824, not from the oral presentation.

At the same meeting, Conybeare presented a major paper on Plesiosaurus.

Sources

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What the sources leave uncertain

February 20 is securely printed as the date the paper was read. The exact day on which the Transactions part was physically published is not established by the sources consulted, so the meeting date should not be called the publication date.
Buckland established the genus Megalosaurus without a species epithet. Megalosaurus bucklandii dates to Mantell's 1827 work.
Some isolated fossils discussed in early histories, especially Robert Plot's lost femur fragment, can only tentatively be assigned to Megalosaurus.